Multiple Fano resonances in all-dielectric porous array structures

Abstract

High Q metasurfaces play an important role in fields such as high-sensitivity sensing and nonlinear optics due to their strong localized electromagnetic field enhancement. Although ultra-high Q resonance has been developed in the field of optics, it is still a challenging task due to the loss of dielectric materials, design and fabrication of nanostructures. In this paper, we have designed an all-dielectric symmetric perforated array structure that supports multiple Fano resonances within the 0–1 THz range and realizes the anapole mode through this array perforation structure. By calculating the phase difference between different modes at the resonance frequencies, we explain the mechanism of the formation of resonance-coupled BIC. The Q-factors of the three modes have been calculated, where the highest Q-value can be up to 2703, it is excited by the MQ. Then, we analyzed the sensing performance and the highest sensitivity can reach 27,000 nm/RIU. Since the metasurface always maintains $c\_4v$ symmetry and mirror symmetry, all three resonances are polarization independent. The proposed metasurfaces can be applied to light-matter interactions, enhanced nonlinear response, and sensing.